1. Field of the Invention
The present invention relates to a power supply cut off apparatus for an electrical vehicle. More the present invention relates to a power supply cut off apparatus for an electrical vehicle, which can assure isolate power supply upon the detection of an abnormal condition of the electrical vehicle.
2. Description of the Related Art
In recent years, there has been a growing interest in the environment of the earth, and an increasing social demand for preventing natural environmental disruption and global warming due to air pollution, and worsening of residential space due to noise. Under these circumstances, an electrical vehicle, which does not always use an internal combustion engine as a driving source, but rather drives a vehicle using clean electric power as a driving source, is receiving a lot of attention, and has been widely studied and developed.
The electrical vehicle may comprise a large-capacity driving power supply, and an electrical motor that is rotated by an electric power supplied from the driving power supply to obtain a driving force to the vehicle.
Since the electrical vehicle comprises a driving circuit for an electrical motor, the electrical motor is driven with a voltage higher more than that of other electrical components, such as power windows.
For example, in a conventional electrical vehicle, the positive and negative terminals of the driving power supply are arranged to electrically float from a body, independently of a low-voltage power supply for other electrical components, which power supply is grounded to the body at the negative terminal.
An internal combustion engine vehicle using a gasoline engine comprises the following battery cut off apparatus against collision.
Japanese Utility Model Publication No. 2-59052 discloses an arrangement for cutting off a power supply from a battery to the respective portions of the vehicle upon collision. Japanese Patent Laid-Open No. 58-224833 also discloses an arrangement for quickly cutting off a power supply from a battery power supply to the respective portions of the vehicle. The power supply is cut off upon collision in a vehicle having a gasoline engine for the following reason. That is, when a gasoline leaks upon collision, an electrical spark generated by a short-circuited battery may ignite the leaking gasoline.